1. Field of the Invention
The present invention relates generally to cationic surfactants, and more particularly, relates to cationic surfactants with asymmetric side chains, especially useful for cosmetic compositions, particularly applications in hair and skin care.
2. Background Information
“Esterquats” are generally understood to be quaternized fatty acid triethanolamine ester salts which are broadly suitable both for softening fibers and for conditioning hair. In the last decade, these substances have significantly displaced conventional quaternary ammonium compounds from the market, for example, distearyl dimethyl ammonium chloride, by virtue of their better ecotoxicological compatibility. Reviews of this subject have been published since the early 1990s, for example, by O. Ponsati in C. R. CED-Congress, Barcelona, 1992, page 167, by R. Puchta et al. in Tens. Surf. Det. 30, 186 (1993), by M. Brock in Tens. Surf. Det. 30, 394 (1993) and by R. Lagerman et al. in J. Am. Oil. Chem. Soc., 71, 97 (1994). Since that time, various types of esterquats and also “amidequats” have been synthesized so that an extensive state of the art is now available for the one looking for an adequate esterquat to solve his specific problem. Nevertheless, one can still find gaps where the products known from the market or from the literature do not meet the requirements of the market, especially in cases where the customer expects that the products fit into a complex profile.
For example, EP 00614349 B1 (Henkel) discloses acidic hair care compositions comprising esterquats and fatty alcohol (polyglycol ethers). The esterquats may be obtained from fatty acids comprising 6 to 22 carbon atoms, however, the preferred acids include at least 12 carbon atoms. Also, the working examples are limited to those esterquats which were obtained from technical grade C16/18 fatty acids based on beef tallow or palm oil. The reference discloses only those species having long or medium, and therefore, symmetric, side chains. The disadvantage associated with the use of such esterquats comes from the fact that on one hand viscosity is too high and too unstable for the formulation of pump sprays, and the application properties, in particular, combability and softening performance, leave room for improvement.
There remains a need for esterquats which overcome the disadvantages mentioned above.